Types

<?php
   $mystring = "12";
   $myinteger = 20;
   print $mystring + $myinteger;
?>

<?php
   $mystring = "wombat";
   $myinteger = (integer)$mystring
?>

<?php
   $mystr = "Jello, world?";
   $mystr{0} = "H";
   $mystr{12} = "!";
   print $mystr;
?>

<?php
   $foo = 1;
   if (isset($foo)) {
      echo "Foo is set\n";
   } else {
      echo "Foo is not set\n";
   }

   if (isset($bar)) {
      echo "Bar is set\n";
   } else {
      echo "Bar is not set\n";
   }
?>